Telephone-exchange system



(No Model.)

J. I. SABIN & W. HAMPTON. TELEPHONE EXCHANGE SYSTEM.

No. 518,331. Patented Apr. 17, 1894.

WZZTLJJJ. I wzmm W UNITED STATES PATENT OFFICE,

JOHN I. SABIN AND WILLIAM HAMPTON, OF SAN FRANCISCO, CALIFORNIA.

TELEPHONE-EXCHANGESYSTEM.

SPECIFICATION forming part of Letters Patent No. 518,331, dated April17,1894. pplication file January ,1894. Serial No. 497,414. (No model.)

1 of this specification.

Our invention relates to telephone systems, and its object is to reduceand render more uniform the time required to secure connection, and toprovide means whereby signals for disconnection and for calling may betransmitted to the central station with minimum exertion on behalf ofthe subscriber.

Our invention in its preferred embodiment comprises means whereby thesubscriber may automatically signal the operator for connection anddisconnection by removing the telephone receiver from its hook in thefirst instance, and by replacing it thereon in the second instance.Again, means are provided whereby one of two connected subscribers maytransmit to the operator a selective signal indicating a desire forconnection with another subscriber, and, further, the necessity of theoperators bridging her telephone into circuit to determine whether ornot the conversation is completed, is obviated. An individual callingindicator and a battery are included in a bridge at the central station,the circuit through the battery being nor mally open at thesubscribers'station whereby the subscriber, by closing the circuit, mayactuate the indicator to signal the operator. A battery and aclearing-out indicator are included in a bridge between the strands ofthe cord connectors at the central station, circuit through the batterybeing closed so long as the subscribers reinainin conversation toactuate the indicator and give the visual busy signal. When, however,the subscribers hang up their telephones, circuit through the bat-. teryis interrupted, and the indicator conveys the signal for disconnection.Instead of the one clearing-out indicator, two maybe used placedin thestrands, one upon each slde of the bridge containing the battery, andwhen so employed, a clearing-out indicator 1s individual to each of twoconnected subscribers.

We will describe our invention in connection with the accompanyingdrawings, in which- Figure l is a diagrammatic view showing twosubscribers connected together for con-v versation, after the manner ofour invention. Fig. 2 is a diagrammatic view showing amannor of applyingour invention to multiple switch board systems. 7

Like letters refer to like parts throughout both views.

In Fig. l we have illustrated the subscribers lines extending to asingle board at the central station, it being understood that ourinvention may equally be applied to multiple boards, as illustrated inFig. 2, or by extend ing-the lines to switches in multiple at otherboards, in which case it would be preferable to extend the local circuitcontaining the calling indicator through the several spring jacks sothat a connection made at any board would serve to cut the indicatorfrom circuit. The spring jacks at the switch board comprise each a pairof springs a b, a 17', adapted to make contact respectively with thesleeve and the tip of a plug adapted to be inserted therein. The springsnormally rest against contact anvils c d, c d, which are connected tothe opposite sides of asource of electricity, such as a battery e, agalvanometer f, or other device responsive to the passage of an electriccurrent being provided in circuit with the battery and mounted upon theboard so that it may be observed by the operator. The several circuitsthus formed, through the individual indicators f f and the battery 6 arenormally open at the subscribers stationto the passage of the continuousbattery current, while means are. provided at the subscribers stationwhereby he may close the circuit, thus completing the battery circuitthrough his particular individual indicator to signal theoperatorforconnection.

We preferably secure thenormal opening of.

the circuit at the subscribers station .by so arranging the telephonehook that when the telephoneis hung thereon thecircuit is maintainedopen, but is closed when the telephone is removed therefrom.

The subscribers bell g is included in abridge between the two sides ofthe line and is included in circuit with a condenser g so that thebattery current is prevented from traversing the bridge containing thebell. The battery circuit is thus controlled entirely by the subscribershook switch, being closed when the telephone is removed, and open whenthe telephone is hung up. The condenser permits the passage of thealternating current from the operators generator.

The central station apparatus comprises a number of pairs of plugs, butone pair h 7?. being shown in the drawings, each plug being providedwith a tip adapted to make contact with the shorter of the line springs,and with a sleeve adapted to make contact with the longer of the linesprings. The tips and the strands of the plugs are respectivelyconnected together by tip and sleeve strands it. In a bridge between thetwo strands is included a battery 75 and a clearing-out indicator Z.Instead of the single clearing-out indicator, a pair of indicators Z Zone individual to each of the subscribers, may be employed, placed inthe strands, one upon each side of the bridge containing the battery.

Ringing keys 'm m are provided adapted, when depressed, to sever theconnection be tween the plugs and to connect one of the plugs with thecalling generator at. The operators telephone set m is included in abridge between the tip and sleeve strands, a bridgingin key m beingprovided adapted to connect or disconnect the telephone set.

We will now describe the several operations necessary to secureconnection between two subscribers. Subscriber A, desiring connec tionwith subscriber B, removes his telephone from the hook, thus completingthe circuit of battery 6 through individual indicatorf, therebynotifying the operator, who inserts plug h into the spring jack ofsubscriber A, the springs or 1) being thereby moved away from thecontact anvils c d to open the circuit through the individualindicatorf. The operator next bridges her telephone into circuit andreceives from A the number of the called subscriber B. She then insertsplug h into the spring jack of subscriber B. If B is engaged inconversation with some other subscriber through a connection at anotherboard, there will be a difference of potential between springs a and b,and the closing of the circuit through the operators telephone by theinsertion of the plug, will cause a click in the telephone, indicatingthat the line is busy. If the line be not busy she will hear no clickupon inserting the plug, and she will then depress ringing key m',thereby sending current from the alternating current generator n throughBs bell, the alternating current passing freely through the bridgecontaining the condenser and bell. B having removed his telephone fromits hook, is in communication with A, and the operator cuts out hertelephone. When the subscribers have completed conversation and hang uptheir telephones, the clearing-out indicator 1 informs the operator ofthe fact and she removes the plugs.

It will be observed that when each subscriber has an individualclearing-out indicator, as indicated in dotted lines, the operator maycut out her telephone as soon as the plug has been inserted in thespring jack of the called subscriber, the fact that the calledsubscriber has responded and is in communication being indicated by thevisual signal of his individual clearing-outindicator. And when eitherdouble or single clearing-out indicators are employed, the operator isnot at the necessity of bridging her telephone into circuit from time totime to learn if the subscribers are through conversation and haveforgotten to ring off, as has been necessary heretofore, for so soon asthe telephone is hung up at the completion of the conversation, theclearing out indicator visually conveys this fact to the operator.

Should one of the connected subscribers desire a reconnection with someother subscriber, he has but to move his telephone hook up and downseveral times, thus causing the visual signal of the clearing outindicator to rapidly change, to attract the attention of the operator.

In an application, Serial No. 490,950, filed November 15, 1893, we havedescribed a telephone system similar in some respects to the presentinvention, and so far as matter shown therein is claimed in the presentapplication. Said application is to be considered subsidiary hereto, andvice versa.

Our invention is susceptible of many modi fications, and we do not,therefore, desire to limit ourselves to precise details.

Having described our invention, what we claim as new, and desire tosecure by Letters Patent, is-

1. In a telephone system, the combination with a metallic circuittelephone line, of an individual indicator and battery in a bridge ofsaid circuit at the central station, a calling device in a permanentbridge of the subscribers station, means at the subscribers station forshort-circuiting said permanent bridge to close said battery operativelyin circuit with said indicator to operate the same, and means forcutting out said battery and indicator when connection is made at thecentral station with said metallic circuit, substantially as described.

2. In a telephone system,"the combination with a metallic circuittelephone line, of an individual indicator and battery at the centralstation in a bridge of said metallic circuit, a permanent bridge at thesubscribers station containing a calling device, a normally opentelephone circuit around said bridge, and means for closing saidtelephone circuit to include said battery operatively in circuit withsaid individual indicator to actuate the same, substantially asdescribed.

3. In a metallic circuit telephone system,

an individual annunciator and battery at the central station in a bridgeof the metallic circuit, a condenser and bell at the subscribersstat-ion connected in a'permanent bridge of said metallic 1 circuit, anormally open telephone circuit around said bell circuit, and means atthe subscribers station for shortcircuiting said bell circuit,substantially as described.

4. In a metallic circuit telephone system, an individual an nunciatorand battery at central station in a bridge of the metallic circuit, anormally open telephone circuit at the subscribers station, means forclosing said telephone circuit and means for cutting out saidannunciator and battery, substantially as described.

5. In a metallic circuit telephone system, an individual annunciator andbattery at central station connected in a separable bridge of themetallic circuit, a condenser and bell at the subscribers stationconnected in a permanent bridge of said metallic circuit, a normallyopen telephone circuit and means for closing same at subscribersstation, to shunt the bell circuit, substantially as described.

6. In a metallic circuit telephone system, an individual annunciator andbattery at central station connected in a bridge of the metalliccircuit, a condenser and bell at the subscribers station connected inanother bridgeof said metallic circuit, a normally open telephonecircuit, means for closing same,and means for cutting out saidannunciator and battery, substantially as described.

7. In a metallic circuit telephone system, an individual annunciator andbattery at central station connected in a bridge of the 1116- talliccircuit, a condenser and bell at the subscribers station connected inanother bridge of said metallic'circuit, a normally open telephonecircuit, means for closing same, a clearing out annunciator at thecentral station, and means for simultaneously cutting out saidindividual annunciator and battery, and

Y cutting in said clearing out annunciator, substantially as described.

8. In a telephone system, the combination with a metallic circuitconnecting two subscribers stations and including the primary of thetransmitter induction coil at each station, of two clearing outannunciators at the central station, and a battery included in a bridgeof said metallic circuit between said clearing out annunciators,substantially as described.

9. In a telephone system, the combination with a metallic circuitconnecting two subscribers stations, of a bridge at each of saidstations containing a bell and condenser,

clearing out annunciators at the central station, a battery included ina bridge of said metallic circuit between said clearing out annunciatorsand a generator adapted to be connected through said metallic circuitwith either one of \said subscribers stations, substantially asdescribed.

10. In a metallic circuit telephone system, the combination withacondenser and bell permanently connected in a bridge of the metalliccircuit at each subscribers station, of a battery connected in aseparable bridge of each of said circuits, an individual indicator incircuit therewith a generator at the central station adapted to betemporarily connected in individual circuit with each bell andcondenser, substantially as described.

.11. In a metallic circuit telephone system, the combination with anindividual annunciator and battery in a bridge of the metallic circuitat the central station, of means for automatically cutting out saidbattery and indicator when connection is made at central station withsaid metallic circuit, and a generator at the central station adapted tobe looped into said metallic circuit.

12. In a telephone system, the combination with a telephone 'lineextending to the central station, of a battery and an individualindicator in a bridge at the central station, means for cutting saidbattery and individual indicator from line by the act of makingconnection therewith at the central station, and a battery andclearing-out indicator adapted to be bridged between the two sides ofsaid line by said act of connecting with the line, substantially asdescribed.

13. In a telephone system, the combination with a battery and individualindicator in a bridge of the telephone line at the central 10o station,of means at the subscribers station for operatively closing said batteryin circuit with said indicator to operate the same, means for cuttingsaid battery and indicator from the line by the act of making connectiontherewith at the central station, a clearing-out indicator, a batteryadapted to be bridged between the two sides .of the telephone line bythe act of connecting therewith, and means at the subscribers stationfor controlling the circuit of said battery through said clearing-outindicator,substantially as described.

In witness whereof we hereunto subscribe our names this 2d day ofJanuary, A. D. 1894. '115 JNO, I. SABIN. WM. HAMPTON. Witnesses: JNo.-A.MALLORY,

WM. F. MARTIN.

